Thin Film Transistor Liquid Crystal Display (TFT-LCD), as a flat-panel display device, is more frequently applied to high-performance display field, due to its characteristics such as small size, low power consumption, no radiation and relatively low fabrication cost.
A TFT-LCD, as shown in FIG. 1a, comprises an array substrate 10 and a color filter substrate 11. A liquid crystal layer 12 is filled between the array substrate 10 and the color filter substrate 11. In addition, a first polarizer 13 is provided on an upper surface of the color filter substrate 11, and a second polarizer 15 is provided between the array substrate 10 and a backlight module 14, and an optical axis of the first polarizer 13 and an optical axis of the second polarizer 15 are perpendicular to each other. In the case that no electric field is applied to the liquid crystal layer 12, light emitted from the backlight module 14 is incident on the liquid crystal layer 12 through the second polarizer 15, the light is rotated by the liquid crystal molecules of the liquid crystal layer 12 during traveling through the liquid crystal layer 12, and then the light is emitted from the first polarizer 13. In the case that an electric field is applied to the liquid crystal layer, an arrangement direction of the liquid crystal molecules in the liquid crystal layer 12 changes, so that the incident light cannot pass through the TFT-LCD. In this way, intensity of light emitted from the TFT-LCD can be controlled. In addition, under a filtering effect of the color filter substrate 11, color image display can be implemented.
In the case shown in FIG. 1a, the above-described polarizers (the first polarizer 13 and the second polarizer 14) may be made of a polyvinyl alcohol (PVA) film. The polarizer allows one polarization component in natural light to transmit, while the other polarization component is absorbed by the polarizer. As a result, a lot of light loss will be caused, so that utilization of the light from the backlight module 14 is greatly reduced.
In order to solve the above-described problem, a wire grid polarizer 20 made of a metal material is employed, as shown in FIG. 1b. In the case that light is incident on the wire grid polarizer 20, under an oscillatory action of free electrons on a surface of the metal wire grid polarizer 20, almost all light having an electric field vector component parallel to the wire grid is reflected, and almost all light having an electric field vector component perpendicular to the wire grid is transmitted. In addition, the light reflected by the wire grid polarizer 20 can be reused. Thus, the utilization of light is effectively improved.
However, in a process of fabricating the above-described metal wire grid polarizer 20, it is necessary to form a metal layer by using a metal target material, and it is also necessary to pattern the metal layer to form the pattern of the wire grid polarizer 20 by a relatively highly accurate etching process. Therefore, the fabrication process thereof is complicated, with great processing difficulty and high fabrication cost.